The invention relates generally to gas turbine engines, and more particularly, to methods for depositing a coating on a selective area of a turbine component.
At least some known gas turbine engines include rotating components which may contact or “rub” adjacent stationary components during normal engine operation. For example, compressor rotor blades are sized such that a tip of the rotor blade “rubs” an adjacent shroud, thus forming a seal between the compressor rotor blade and the shroud.
To facilitate reducing damage to the compressor rotor blades, at least some known gas turbine engine rotor blades are coated with a wear resistant coating material. Such coatings are generally used to facilitate reducing a rate of wear of the blade caused when the blade contacts a surrounding shroud. Other wear coatings may be deposited along a leading edge of the turbine blade to facilitate decreasing wear caused by contact with environmental particulates, e.g., dirt, sand, that enter the turbine engine during operation. Another type of known wear coating is deposited across components of the turbine engine that are susceptible to wear caused by part-to-part contact during operation. For example, in a high pressure turbine (HPT) and/or a low pressure turbine (LPT) section of a gas turbine engine, wear coatings may be deposited on pre-determined areas of vane sectors that may rub against an adjacent structure, such as a shroud hanger or a pressure balance seal.
At least one known method of depositing a wear coating onto a surface of a gas turbine engine vane sector requires machining a plurality of individual components of the vane sector, depositing a coating material onto an outer surface of the machined components, and then brazing the coated components to produce an inseparable gas turbine vane sector that may be installed in the gas turbine engine. However, applying the wear coating prior to brazing the individual components may require several steps. For example, the components must be masked to prevent the wear coating from being deposited on portions of the component that are not subject to part-to-part wear. Accordingly, coating the separate components prior to assembling the final component, may result in additional fabrication costs, and may thereby increase the overall cost of the component.